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A method for preparing ammonium fluoride by tertiary amine-fluorosilicic acid

A technology of fluorosilicic acid and ammonium fluoride, which is applied in the direction of ammonium fluoride, ammonium halide, silicon oxide, etc., can solve the problems of unstable ammonium fluoride, low total fluorine yield, burden, etc., and achieve the reduction of waste of water resources, The effect of high total yield and reduction of production energy consumption

Active Publication Date: 2017-09-22
YUNNAN TIANAN CHEM CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages of this process route are as follows: (1) Since the raw material dilute fluorosilicic acid contains a large amount of water (usually the water content is about 90%), only dilute ammonium fluoride aqueous solution can be prepared, and the target product fluorine fluoride cannot be obtained. (2) Since ammonium fluoride is extremely unstable and decomposes in hot water, even after concentrating the ammonium fluoride aqueous solution, the target product ammonium fluoride solid cannot be obtained, and only ammonium bifluoride solid can be obtained (the above-mentioned document It has been reflected); (3) During the concentration process, a large amount of water brought by dilute fluorosilicic acid needs to be evaporated, so the energy consumption is high; (4) Concentration will produce a large amount of dilute ammonia water containing fluorine, resulting in (a) the water cannot be returned to Phosphate rock decomposition tail gas absorption system, so that the wet-process phosphoric acid and phosphate fertilizer enterprise systems cannot achieve water balance, (b) produce a large amount of fluorine-containing dilute ammonia water and it is difficult to reuse, causing a great burden on enterprise wastewater treatment, (c) ) Due to the large amount of fluorine contained in dilute ammonia water, the total yield of fluorine is low; (5) During the ammonium fluoride concentration process, the ammonium bifluoride produced is highly acidic and corrosive, so the requirements for concentration-related equipment are high
These technical defects have greatly restricted the application of the above-mentioned process route in industrial production

Method used

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  • A method for preparing ammonium fluoride by tertiary amine-fluorosilicic acid

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Experimental program
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Effect test

Embodiment 1

[0034] Stir and extract 1000 g of dilute fluorosilicic acid with a mass fraction of 5% and 1000 g of tri-n-octylamine at 50°C for 10 minutes, then stand still for 10 minutes to separate the phases to obtain tri-n-octylamine-fluorosilicic acid and water phase; pass 42.5 g of ammonia gas into tri-n-octylamine-fluorosilicic acid, stir and react at 20°C for about 30 min, and filter to obtain the filter cake and filtrate; add 200 g of 50% ammonium fluoride aqueous solution to the filter cake , after stirring at 50°C for about 20 min, filter at 50°C, wash the filter cake, and dry to obtain white carbon black solid and supersaturated ammonium fluoride solution. solid.

[0035] In this process, the extraction rate of fluosilicic acid is 99.2%; the yield of white carbon black is greater than 99%, the purity is greater than 98%, and the specific surface area is 161 m 2 / g; the yield of ammonium fluoride was 95.6%, and the purity was 95.8%.

Embodiment 2

[0037]1000 g of dilute fluorosilicic acid with a mass fraction of 18% and 2000 g of tri-n-heptylamine were stirred and extracted at 90°C for 20 minutes, and then allowed to stand for 10 minutes to separate phases to obtain tri-n-heptylamine-fluorosilicic acid and an aqueous phase ; Pass 153 g of ammonia gas into tri-n-heptylamine-fluorosilicic acid, stir and react at 20°C for about 60 min, filter to obtain filter cake and filtrate; add 600 g of 50% ammonium fluoride aqueous solution to the filter cake, After stirring at 50°C for about 20 minutes, filter at 50°C, wash the filter cake, and dry to obtain a white carbon black solid and a supersaturated ammonium fluoride solution. The supersaturated ammonium fluoride solution is crystallized and dried at a lower temperature to obtain a solid ammonium fluoride .

[0038] In this process, the extraction rate of fluosilicic acid is 99.5%; the yield of white carbon black is greater than 99%, the purity is greater than 98%, and the spec...

Embodiment 3

[0040] 1000 g of dilute fluorosilicic acid with a mass fraction of 12% and 1800 g of tri-n-decylamine were stirred and extracted at 80°C for 20 minutes, and then allowed to stand for 10 minutes to separate the phases to obtain tri-n-decylamine-fluorosilicic acid and the aqueous phase ; Pass 102 g of ammonia gas into the tri-n-decylamine-fluorosilicic acid, stir and react at 40°C for about 40 min, filter to obtain the filter cake and filtrate; add 480 g of 50% ammonium fluoride aqueous solution to the filter cake, After stirring at 30°C for about 20 min, filter at 30°C, wash the filter cake, and dry to obtain white carbon black solid and supersaturated ammonium fluoride solution. .

[0041] In this process, the extraction rate of fluosilicic acid is 98.4%; the yield of white carbon black is greater than 99%, the purity is greater than 98%, and the specific surface area is 181 m 2 / g; the yield of ammonium fluoride was 93.7%, and the purity was 96.4%.

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Abstract

The invention relates to a method for preparing ammonium fluoride from tertiary amine-fluosilicate. The method includes the process steps that firstly, tertiary amine is added into diluted fluosilicic acid to serve as an extraction agent, a tertiary amine-fluosilicate solution and an aqueous phase which cannot be dissolved in water are obtained after extraction layering, and the aqueous phase returns to a phosphorite decomposed tail gas absorbing system to absorb silicon tetrafluoride; secondly, ammonia gas is introduced into the tertiary amine-fluosilicate solution in the first step and stirred, and then an ammonium fluoride and silicon dioxide mixture filter cake and tertiary amine filtrate are obtained through filtration; thirdly, the tertiary amine filtrate obtained through filtering in the second step is returned to the first step to extract the diluted fluosilicic acid; fourthly, an ammonium fluoride saturated aqueous solution is prepared at the temperature of 0 DEG C, an ammonium fluoride and silicon dioxide mixture obtained after being heated is added into the solution, and a supersaturated ammonium fluoride solution and silicon dioxide are obtained respectively through stirring, washing, heat preserving and filtering; fifthly, the silicon dioxide is washed and dried, and white carbon black is obtained; sixthly, the supersaturated ammonium fluoride solution is cooled below the temperature of 0 DEG C, and ammonium fluoride mother liquor is heated and then recycled.

Description

technical field [0001] The invention relates to a production method in the chemical industry, in particular to a method for preparing ammonium fluoride from tertiary amine-fluorosilicic acid. Background technique [0002] A large number of fluorine-containing compounds are by-produced in wet-process phosphoric acid and phosphate fertilizer enterprises. These fluorine-containing compounds mainly exist in the form of dilute fluorosilicic acid, which are toxic and corrosive to a certain extent. Direct discharge will cause serious pollution to the environment. If dilute fluorosilicic acid can be effectively utilized, it will not only reduce pollution, but also convert the contained fluorine and silicon elements into fluorine and silicon products with higher economic value, so that the utilization of fluorosilicic acid will be raised to a new level. To achieve high-value utilization of dilute fluorosilicic acid, it is first necessary to select appropriate fluorine and silicon pro...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01C1/16C01B33/12
CPCC01B33/12C01C1/162
Inventor 黄天江杨胜军田强李国鹏张宗凡黄忠李玉叶
Owner YUNNAN TIANAN CHEM CO LTD